Partially acetylated, cyanoethylated cotton textile fibers and process of acetylating cyanoethylated cotton textile fibers



2,825,623 Patented Mar. 4, 1958 PARTIALLY ACETYLATED, CYANOETHYLATED COTTON TEXTILE FIBERS AND PROCESS OF ACETYLATING CYANOETHYLA-TED COTTON TEXTILE FIBERS James R. Stephens and Lorence Rapoport, Stamford, Conn, assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing.- Application June 30, 1955' Serial No. 519,264

4' Claims. (Cl. 8-129).

This invention relates to partially acetylated, cyanoethylated alpha-cellulose textile fibers, such as acetylated, cyanoethylated cotton yarn, having the original fiber structure and more particularly the invention relates to processes of producing such materials from partially cyanoethylated cotton textile fibers having the fiber structure of the original cotton and containing free hydroxyl groups, cyanoethyl ether groups and from about 3% to about of nitrogen, by weight, of said fibers, the nitrogen being nitnle nitrogen in the cyanoethyl groups thereof.

Cellulose acetate fibers have achieved a very great use in many types of fabrics. However, the cellulose acetate has been strictly a synthetic fiber, that is to say, the acetylated cellulose is dissolved up in solvents and spun by extrusion from spinnerettes. As a result monofilaments are produced which have the advantages of this type of fiber but also its disadvantages, such as a difierent hand, surface, characteristics and the like.

According to the present invention, instead of acetylating cellulose, a cyanoethylated alpha-cellulose, such as cyanoethylated cotton yarn, is acetylated to introduce some acetyl groups and we have found that in this way it is possible to retain the general physical characteristics of cotton yarn and to improve certain properties. In doing so, the cyanoethylated cotton textile fibers are partially acetylated by reacting them with acetic anhydride to introduce at least 0.3 mole of acetyl group per anhydroglucose unit of the cellulose, as shown in the example given post. Further, as there shown, the acetylation is insufiicient to acetylate all of the free hydroxyl groups thereof and insufiicient to destroy the fibrous structure of the cyanoethylated cotton fibers.

Cyanoethylation of alphacellulose, such as cotton, has become of increased interest in recent years because of the desirable properties obtained, such as increased tensile strength, resistance to microorganisms, such as those causing mildew, increased abrasion and heat resistance, and the like. With alpha-cellulose, such as cotton, the cyanoethylation is carried out until only a portion of the hydroxyl groups of the anhydroglucose cellulose unit are cyanoethylated. In general, in order to retain the fiber structure and desirable properties, the amount of cyanoethylation should vary between that giving a nitrogen content of about 3% up to around 5%, by weight, of the cyanoethylated cotton fibers. Somewhat higher degrees of cyanoethylation may be utilized without losing all of the fiber characteristics. When the acetyl groups are introduced into the cyanoethylated cotton the fiber structure is not materially changed and there is not produced a single solid filament such as the ordinary cellulose acetate fiber. As a result the good hand and other physical properties of the cotton fiber are retained.

The present invention should not be confused with a procedure which has been proposed in the past in which ligno-cellulose, not alpha-cellulose, is cyanoethylated to the point that it loses entirely its fibrous structure and is then acetylated. This results in a product which has to be dissolved and spun exactly as ordinary cellulose acetate and has none of the properties of the original lignocellulose fiber. In other words, a product is produced which bears no relation to that of the present invention.

It is an advantage of the present invention that the acetylation process used is not critical and any standard procedures may be employed. As the particular acetylation process technique forms no part of the present invention, a single representative method only will be described in the following specific example.

Example 17.3 parts of 40 S72 cotton yarn cyanoethylated to a nitrogen content of 3.31% nitrogen, 200 parts of pyridine and 200 parts of acetic anhydride are heated on a steam bath with gentle stirring until acetylation under these conditions is substantially complete. This does not mean that all hydroxyl groups of the cellulose are acetylated but that the reaction has proceeded about as far as it will under the conditions set forth. The yarn is then removed from the acetylating bath, washed in running water until free of acetic acid and dried at 70 C. On analysis for acetyl groups the product showed the acetylation to a degree of .3 mole of acetyl group per anhydroglucose unit of the cellulose.

The product had an excellent hand and the following physical characteristics:

The tensile strength is markedly in excess of that of ordinary cotton yarn of the same character which has a tensile strength of about 600 grams, elongation is increased, and tenacity remains substantially the same. The tensile strength and elongation are substantially the same as for the cyanoethylated cotton before acetylation. The denier is somewhat greater showing a moderate degree of swelling.

We claim:

1. The partially acetylated, cyanoethylated cotton textile fibers having the fibrous structure of the original cotton and containing both acetyl groups and cyanoethyl ether groups in addition to free hydroxyl groups, the so modified cotton fibers having a tensile strength greater than that of the original cotton fibers and containing at least 0.3 mol of acetyl group per anhydroglucose unit thereof and from about 3% to about 5% of nitrogen, by weight, of said fibers, the nitrogen being present as nitrile nitrogen in said cyanoethyl groups thereof.

2. The partially acetylated, cyanoethylated cotton textile fibers of claim 1 which contain approximately 0.3 mol of acetyl group per anhydroglucose unit thereof.

3. As a process of producing partially acetylated, cyanoethylated cotton textile fibers having the fibrous structure of the original cotton and containing a plurality of cyanoethyl ether groups, acetyl groups and free hydroxyl groups, from partially cyanoethylated cotton textile fibers containing free hydroxyl groups and cyanoethyl ether groups, containing from about 3% to about 5% of nitrogen, by weight, of said cyanoethylated fibers, the nitrogen being present as nitrile nitrogen in said cyanoethyl groups thereof, and having the fiber structure of the original cotton and a tensile strength greater than that of the original cotton fibers, the improved process which comprises partially acetylating the said partially cyanoethylated cotton textile fibers with acetic anhydride in an inert organic solvent to convert only part of the free hydroxyl groups thereof into acetyl groups and produce partially acetylated, cyanoethylated cotton textile fibers having the fibrous structure of the original cotton and containing at least 0.3 mol of acetyl group per anhydroglucose unit thereof, said acetylation being insuflicient to substantially destroy the fibrous characteristics of the said cotton textile fiber, insulficient to materially weaken the tensile strength thereof and insufiicient to acetylate all of the free hydroxyl groups thereof, and recovering the partially acetylated cyanoethylated cotton textile fibers so obtained, the modified cotton textile fibers so produced being partially acetylated, cyanoethylated cotton textile fibers having the fibrous structure of the original cotton and a tensile strength greater than that of the original cotton fibers and containing both cyanoethyl ether groups and acetyl groups, in addition to free hydroxyl groups.

4. A process of producing an acetylated material from cyanoethylated cotton textile fibers having a nitrogen content of approximately 3.3%, by weight, of said fibers, the nitrogen being present as nitrile nitrogen in said cyanoethyl groups thereof, and a degree of cyanoethylation insuflicient to substantially destroy the fibrous characteristics of the cotton, which comprises acetylating said cyanoethylated cotton textile fibers at the temperature of a steam bath with an excess of a liquid consisting of equal parts of pyridine and acetic anhydride, the reaction being maintained until substantially complete and the acetylation proceeding to a point where the fiber characteristics of the cyanoethylated cotton are still retained, and then washing the so treated yarn free of acetic acid.

References Cited in the file of this patent UNITED STATES PATENTS Haller Oct. 17, 1933 Stallings June 14, 1949 OTHER REFERENCES 

1. THE PARTIALLY ACETYLATED, CYANOETHYLATED COTTON TEXTILE FIBERS HAVING THE FIBROUS STRUCTURE OF THE ORIGINAL COTTON AND CONTAINING BOTH ACETYL GROUPS AND CYANOETHYL ETHER GROUPS IN ADDITION TO FREE HYDROXYL GROUPS, THE SO MODIFIED COTTON FIBERS HAVING A TENSILE STRENGTH GREATER THAN THAT OF THE ORIGINAL COTTON FIBERS AND CONTAINING AT LEAST 0.3 MOL OF ACETYL GROUP PER ANHYDROGLUCOSE UNIT THEREOF AND FROM ABOUT 3% TO ABOUT 5* OF NITROGEN, BY WEIGHT, OF SAID FIBERS, THE NITROGEN BEING PRESENT AS NITRILE NITROGEN IN SAID CYANOETHYL GROUPS THEREOF.
 4. A PROCESS OF PRODUCING AN ACETYLLATED MATERIAL FROM CYANOETHYLATED COTTON TEXTILE FIBERS HAVING A NITROGEN CONTENT OF APPROXIMATELY 3.3%, BY WEIGHT, OF SAID FIBERS, THE NITROGEN BEING PRESENT AS NITRILE NITROGEN IN SAID CYANOETHYL GROUPS THEREOF, AND A DEGREE OF CYANOTHYLATION INSUFFICIENT TO SUBSTANTIALLY DESTORY THE FIBROUS CHARACTERISTICS OF THE COTTON, WHICH COMPRISES ACETYLATING SAID CYANOETHYLATED COTTON TEXTILE FIBERS AT THE TEMPERATURE OR A STEAM BATH WITH AN EXCESS OF A LIQUID CONSISTING OF EQUAL PARTS OF PYRIDINE AND ACETIC ANHYDRIDE, THE REACTION BEING MAINTAINED UNTIL SUBSTANTIALLY COMPLETE AND THE ACETYLATION PROCEEDING TO A POINT WHERE THE FIBER CHARACTERICS OF THE CYANOTHYLATED COTTON ARE STILL RETAINED, AND THEN WASHING THE SO TREATED YARN FREE OF ACETIC ACID. 